Research on this theme is aimed at understanding the progression of dormancy under mild winter conditions and the impact of insufficient winter chill on fruit production. We also study dormancy release to potentially identify new, safer rest-breaking chemicals. Furthermore, it is becoming increasingly evident that the induction of dormancy under mild, local conditions requires further study. To this end, we are utilising the Pro-Hort ecophysiology platform consisting of 10 genotypes each of apple, plum and pear varying in chill (and heat) requirement planted at three climatically contrasting sites. The platform allows the researchers to tease apart the effect of chill and heat requirements on the adaptability of cultivars to local conditions. It will also enable us to correlate the output of the various chill models with vegetative bud break and flowering data to identify the most suitable model for South African conditions.
A new project was initiated to continue the evaluation of effective and safer rest breaking treatments as an alternative to hydrogen cyanamide and mineral oil for pome fruit production. The alternative rest breaking treatments will be compared to hydrogen cyanamide and mineral oil for their ability to reduce delayed foliation, synchronize bud break and achieve consistent high yields.
EXPERTISE: Dormancy Workgroup
Research Team
- Prof Wiehann Steyn
- Dr Esmé Louw
- Dr Nigel Cook
- Dr Tara Southey
- Dr Iwan Labuschagne
- Mr Tristan Dorfling
- Mr Chad van Wyk
- Ms Portia Solomon – MSc student
- Ms Cara du Toit – MSc student
Projects list
- Rest breaking alternatives to hydrogen cyanamide (C van Wyk)
- Climate profiling and change analysis of the Elgin-Grabouw-Vyeboom-Villiersdorp (EGVV), Koue Bokkeveld (KBV) and Langkloof (LK) production areas specific to Pome fruit (T Southey) – see Growing season climate
- Historic and future modelling and mapping of early season temperature patterns and extremes, and impacts for pome and stone fruit production in South Africa (S Midgley) – see Growing season climate
- Adaptability indexing of new pome (apple and pear) and stone fruit (plum and cherry) cultivars in diverse South African growing areas (I Labuschagne, E Louw, A Kock and T Dorfling) – see Growing season climate
- Investigating the significance of temperature on flowering phenology by establishing a South African apple and plum phenophase-temperature database (E Louw and I Labuschagne)
- Growth synchronisation of stone fruit rootstocks and scions with different chilling requirements (C van Wyk) - see Rootstocks and Nursery Tree Quality
- Apple rootstock influence on Granny Smith scion growth, productivity and fruit green colour (T Dorfling) - see Rootstocks and Nursery Tree Quality
- No projects completed.
- Quantifying the impact of insufficient winter chill on apple fruit quality (E Louw and A van Lingen)
- Leaf defoliation of Cripps' Pink and Granny Smith apples in the EGVV - effect on vegetative and reproductive development (X Siboza, K Theron and D Craven) – see Reproductive biology
- Evaluation of alternative rest-breaking agents for apples (X Siboza, K Theron and D Craven) [Abstract]
- Investigating the effect of different autumn/winter scenarios on the spring bud break in apple trees (E Louw and L Allderman) [Abstract]
- Validation of the shoot assay as a proxy to determine the progression of dormancy in intact apple trees (E Louw and L Allderman) [Abstract]
- Evaluate rest breaking programmes for warm winter regions. (X Siboza and D Craven) [Abstract]